On May 15, 2003, about 1130 eastern daylight time, a Schweizer 269C, N109JS, was substantially damaged during a forced landing to a residential area, following a partial loss of engine power in cruise flight near New Canaan, Connecticut. The certificated commercial pilot and the passenger sustained minor injuries. Visual meteorological conditions prevailed for the flight that departed Danbury Municipal Airport (DXR), Danbury, Connecticut, about 1115. No flight plan was filed for the commercial aerial photography flight conducted under 14 CFR Part 91. The pilot stated that the helicopter was in cruise flight at 1,100 feet msl, when he noticed a gradual loss of rotor rpm. The pilot lowered the collective and increased throttle, but the rotor rpm continued to decay. He repeated the procedure as the engine continued to lose power. The pilot set up for a forced landing to a field; however, the helicopter impacted the backyard of a residence prior to the field. The pilot added that the engine never experienced a total power loss. When asked if he entered an autorotation, the pilot stated, "no the needles never split." A Federal Aviation Administration (FAA) inspector observed that the fuselage, tail boom, main rotor, and tail rotor sustained damage. He also noted a rod-end, that mated into the fuel control, was separated. The wreckage was further examined by the FAA inspector, a Safety Board investigator, a representative from the aircraft manufacturer, and a representative from the engine manufacturer. The examination revealed that throttle cable lower bellcrank arm had separated from the fuel control. Two brass bushings (part number AN77A-3-13) were located at the throttle cable lower bellcrank arm assembly. The two brass bushings were found worn. There were also two steel bushings (part number 269A8445-3), which fit underneath the two brass bushings at the lower bellcrank arm assembly. The two steel bushings were not worn. Review of maintenance records revealed that the helicopter underwent an annual inspection from January 13, 2003, thru January 31, 2003. Review of the shop-floor maintenance records (work order number 03-1016) revealed that a mechanic wrote the following discrepancy, "Throttle Cable Bushings (2 ea.) Worn At Lower Bellcrank Arm." However, the part number referred to the steel bushings. The action taken stated, "Removed and inspected found to be within limits, re-installed and safetied," and was initialed by a company inspector. There was no mention of the brass bushings in the shop floor records. The customer invoice stated "Problem: During routine inspection, found throttle cable bushings worn at the lower bellcrank arm assembly...Action Taken: Remove worn bushings an install TSN 0.0 bushings 2 ea. P/N 269A8445-003. All work accomplished in accordance with SAC HMI." The customer was charged $234.55 for the two bushings, freight, and labor; yet a review of the maintenance facility purchase order number 5111 revealed that two throttle bushings (part number 269A8445-003) were returned to the manufacturer on February 3, 2003, for a refund. There was no mention of the brass bushings on the customer invoice or the maintenance purchase order. The helicopter had accumulated approximately 75 hours of operation since the annual inspection. A 25-hour inspection was performed on March 17, 2003, and a 50-hour inspection was performed on April 4, 2003. In addition, the pilot had performed multiple "First Flight of the Day" inspections subsequent to the annual inspection. Review of that inspection checklist revealed, "9. Throttle linkage for excessive play and freedom; contact full open and idle stops. According to the helicopter manufacturer, loose brass bushings would result in looseness in the throttle system. None of the inspections detected the worn brass bushings. Federal Aviation Regulation Part 43, Appendix D, "Scope and Detail of Items to Be Included in Annual and 100-Hour Inspections," (d) pertained to engine components. Number (6) stated, "Engine controls--for defects, improper travel, and improper safetying;" and number (10) stated, "All systems--for improper installation, poor general condition, defects, and insecure attachment."